var $win;
var winW, winPos;
var $mainnav, $mainnav_logo, $mainnav_height;
var $content, $content_height;
var $currentMenuItem;

jQuery(document).ready(function($){
  $win = $(window);
  $(document).on('focus', 'a', function(){ $(this).blur(); });
  $('ul#main_nav').on('click', 'a', function(event){
    //event.preventDefault();
    var target = $(this);
    var item = target.parent();
    if ($currentMenuItem == item) return;
    if ($currentMenuItem != undefined) $currentMenuItem.removeClass('current');
    item.addClass('current');
    $currentMenuItem = item;
  });
  $mainnav = $('#main_nav_container');
  $mainnav_logo = $('#logo', $mainnav);
  $mainnav_height = $mainnav.height();
  $content = $('#content');
  $content_height = $content.height();
  
  if ($content_height > $mainnav_height) {
    positionMenu();
    $(window).on('scroll', positionMenu);
    $(window).on('resize', positionMenu);
  }
});

function positionMenu() {
  var currentW = $win.width();
  var currentT = $win.scrollTop();
  
  if (currentT < 70) {
    if (winPos != 'absolute') {
      $mainnav.css({'position':'absolute', 'left':'auto'});
      $mainnav_logo.css({'padding-top':100});
      winPos = 'absolute';
    }
  } else {
    if (winPos != 'fixed') {
      $mainnav.css({'position':'fixed'});
      $mainnav_logo.css({'padding-top':30});
      positionMenuX(currentW);
      winPos = 'fixed';
    }
    if (currentW != winW) positionMenuX(currentW);
  } 
}

function positionMenuX(windowWidth) {
  winW = windowWidth;
  var left = 820 - $win.scrollLeft();
  if (winW>1000) left += Math.floor((winW - 1000)*.5);
  $mainnav.css('left', left+'px');
}